Spin probes for electron paramagnetic resonance imaging

Electron paramagnetic resonance imaging (EPRI) is a relatively recent imaging technique, which provides potentially multidimensional imaging of the spatial distribution of paramagnetic species. Thanks to the use of stable spin probes, low frequency EPR imaging has recently allowed the use of large tissue samples or whole animals in vivo in the field of biology and medicine. It is normally necessary to introduce prior intravenous or intramuscular infusion of stable or slowly metabolizable non-toxic water-soluble paramagnetic materials, or stable implantable particulate materials as spin probes into the system. The classification and research progress of spin probes at present were described briefly. Three important potential approaches in water-soluble paramagnetic materials design including deuterated, site-specific and macromolecular conjugated nitroxides were also investigated.